Furnace grate



Dec. 6, '1 932.

A. w. BENNIS 1,890,211

FURNACE GRATE Filed Oct. 8, 1928 2 Sheets-Sheet l .9770/F/VEY5.

Patented Dec. 6, 1932 UNITED STATES ALFRED WILLIAM Bil-ENNIS, OF BOLTON, ENGLAND FURNACE GRATE Application filed October 8, 1928, Serial No. 311,169, and in Great Britain November 23, 1927.

The present invention relates to chain grates and the like furnaces and more particularly of that type of grate in which grate bars are mounted on carrier bars extending 4 5 transversely across the grate.

The object of the present invention is to provide an e'liicient and simple form of control for the air supply to the grate.

According to the present invention the air supply to the grate is regulated by dampers travelling with the grate bars.

A plurality of dampers are mounted on the carrier bars supporting the grate bars and are adapted for relative displacement therewith to shut off or regulate the volume of air supply through the grate bars.

Each carrier bar may be provided with one or more dampers or alternatively one damp-er may be provided for alternate carrier bars or even for every third or fourth carrier bar.

The dampers may either be formed as extensions of the base of the carrier bars or may be formed of separate members. Preferably they are of arcuate shape and pivotally mounted to the base of the carrier bars for angular displacement therewith.

It will be appreciated that by reason of the provision of these travelling dampers it is unnecessary to provide compartments beneath the upper run of the grate for varying the air supply to the grate and by this means the cost of a grate fitted with the construction according to the present invention is considerably less than the cost of a grate of similar size and provided with the usual compartments. It will be appreciated however, that if desired the dampers of the present invention, instead of being utilized as an alternative to compartments beneath the upper run of the grate, may be used in conjunction with said compartments, that is, the compartments located below the upper run of the grate will supply air through the damper openings to the grate bars.

The invention is more particularly described with reference to the accompanying drawings, in which Figure 1 is a transverse section across half a chain grate constructed according to the present invention, the other half of the grate being arepetition of that half illustrated.

Figure 2 is a side elevational view of the grate according to Figure 1.

Figure 3 is a plan view of a portion of the grate with the grate bars, carrier bars and dampers removed, and shows the relative disposition of the lever and rod mechanisms for elevating the runner rails adapted to displace the dampers.

Figure 1 is a detailed view on a larger scale of a portion of Figure 2.

In the drawings, the grate comprises a plurality of grate bars 1, which are mounted on transverse carrier bars 2 extending across the grate, these carrier bars being supported on driving chains 11 provided with rollers 14 moving along rails or supports 18 extending longitudinally of the grate, and spaced apart across the width of the grate, the number of such chains 11 and rails 13 being dependent on the width of the grate.

In the grate as shown in the drawings, three sets of chains 11 with their accompanying rollers 14 and rails 13 are provided across half the grate.

The carrier bars 2 have horizontal base portions 4 to one end of which a number of dampers 3 are pivotally mounted as indicated at 5.

A most suitable form of the dampers 3 is the arcuate shape in cross section as illustrated in Fig. 4 of the drawings.

Each damper extends between adjacent compartments 15 enclosing the driving chains or between the end compartments 15 and the sides 16 of the grate. One end of each damper is pivotally mounted to the base 1 of the carrier bar 2 whilst the free end of each damper in the closed position or" this is adapted to engage with the lower surface of the base a of the next succeeding carrier bar 2.

It will be obvious however, that the dampers 3 may be of suiilcient size to overlap the next succeeding carrier bar and engage with the lower surface of the base of the next but one succeeding carrier bar.

By reason oi? the fact that the dampers 3 extend between adjacent casings 15 enclosing the driving chains for the grate and also extend from one carrier bar to another, comrunner rails 6. These runner rails may be divided longitudinally into a number of sections curved or of suitable shape at their ends and preferably are so positioned that each divided portion extends slightly beyond the adjacent edge of the laterally adjacent divided portion, i. e. runner rails 6 in one vertical plane overlap the gap between the runner rails in each vertical plane on either side.

here the runner rails are interrupted to leave a longitudinal gap between longitudinally adjacent runner rails, it will be seen that when a damper 3 in its movement, comes to a position over the gap, it is no longer supported by runner rails, and can swing downward by reason of its own weight, about its pivot 5 to assume a substantially vertical position. Any material which has dropped through the grate bars on to said dampers can therefore be deposited by said dampers into a chute such as that illustrated at 7 in Figures 2 and 4 of the drawings. In Figures 2 and 3 it will be noted that the end piece 6a of the runner rail is spaced from the adjacent movable section 6 of the runner rail by a gap beneath which is located a chute 7a.

By suitably placing chutes along the length of the grate, material according to its state can be independently collected. For example, if a. chute is placed substantially near the front of the grate, fine unburnt fuel can be collected independently of ash or the like which may fall through the grate bars over the remainder of the run of the grate. Such an arrangement is shown, described and claimed in my co-pending application Ser. No. 311,168 filed October 8, 1928.

Thus the ash collected during the remainrzler of such run is discharged into the chute The space between the base 1 of the carrier bars 2 and the runner rails 6 is adapted to be regulated by lever and rod mechanism in order to vary the opening between the free ends of the dampers and the lower surface of the base of the next succeeding carrier bars to those on which the dampers are mounted. In this way, regulation of the air supply into each chamber, the base of which is formed by a damper 3, can be regulated.

In chain grate furnaces where an arch isformed on either side of the grate it is essential that the volume of air supply to the centre position of the dampers relatively to their carrier bars is adapted to be varied along the run of the grate as well as across the grate.

Any means may be devised for displacing the runner rails 6 toclose or open, to any varied extent, the dampers 3.

A suitable form of mechanism for displacing the runner rails is illustrated in the draw ings, and consists of a plurality of spindles 17 18 and 19 having control members preferably in the form of handles 20, 21, 22, respectively, and situated at the sides of the grate, these spindles 17, 18 and 19 being disposed transversely of the grate.

Further, these transverse spindles are repeated (as in Figure 2) at various points along the run of the grate, a set of such spindles being provided at the ends of each length of runner rail 6. Levers 20, 21, 22 are mounted on the spindles 17, 18, 19 respectively and are adapted to be angularly displaced about said spindles when these are rotated by the handles or the like controls at the sides of the grate. The free end of each lever 20, 21, 22 is mounted in a slot of a guide member 30 carrying a vertical rod 23, 24: or 25, respectively, the upper end of each vertical 'rod 23, 24 or 25 carrying one end of a runner rail 6.

' 'As will be seen from Figure 1 of the'drawings, the upper set of controls 20 which are used to rotate the spindles 17 in order to angularly displace the levers 20 and elevate or lower the vertical rods 23, are adapted to regulate the closing or degree of opening of the dampers 3 at each side of the grate.

, The handles or the like controls 21 for rotating the spindles 18 to angularly displace the levers 21 thereby elevating the vertical rods 24 form the controls for the regulation of those dampers situated intermediate the sides of the grate and the central runof the grate, whilst similarly, controls 22 operate the dampers extending from one end of the grate to the'other but centrally of the grate. It will be understood that normally the shafts 17, 18, 19 and their operating handles 20, 21, 22. are so balanced thatthey remain in any adjusted position, automatically and by reason of the-friction of parts.

I declare that what I claim is '1. A furnace chain grate comprising a driving chain, grate bars supported on said chain, and a plurality of trough-shaped dampers pivotally supported on said chain for movement therewith, said dampers operating to control the upward flow of air past themselves to the grate bars, and means for moving said dampers to a selected angular position with respect to their pivotal supports while moving with the chain and grate are whereby to retain material passing through the grate bars and to limit and control the quantity of air moving upward past the dampers to said grate bars.

2. A furnace chain grate as in claim 1, in which the means for moving the dampers comprises a-runner rail extending in the direction of movement of the grate whereby the dampers may be supported against downward swinging movement, said runner rail comprising sections spaced longitudinally apart to leave gaps at a plurality of points along the upper run of the grate whereby the dampers are supported and held in air controlling positions by engagement with the sections and are permitted to individually open by gravity at the said gaps between the spaced sections, means to move said sections individually into regulated positions to control the air flow, and chutes located between the spaced sections to receive the material discharged from the trough-like damper.

3. A furnace chain grate comprising a driving chain, grate bars supported on said chain, a plurality of dampers pivotally supported on said chain beneath said bars to move therewith, each of said dampers being divided transversely of the direction of movement of the grate into a plurality of damper sections, a runner rail extending in the direction of movement of the grate and located beneath each of said sections, each said runner rail comprising a plurality of rail sections spaced longitudinally apart at a plurality of points along the upper run of the grate whereby the damper sections are supported and held in air controlling position by engagement with the respective rail sections and are permitted to individually open by gravity at the gaps between the spaced rail sections, and independent means for raising and lowering the runner rail sections whereby to control the quantity of air admitted past the damper sections to the grate at one pointindependently of the quantity admitted at another point of the width of the grate.

4. A furnace chain grate comprising a plurality of driving chains, a plurality of carrier bars connected to and extending transversely of the direction of movement of said chains, grate bars mounted on said carrier bars, a plurality of trough-shaped dampers, each damper being pivotally mounted on a carrier bar for movement about an axis substantially parallel to the carrier bar, runner rails extending in the direction of the grate and positioned to engage and support the trough-like dampers at the upper run of the grate in position to receive and retain material passing through said grate bars, said runner rails comprising a plurality of sections in the direction of the length of the grate, at least two of said sections being spaced apart to leave a gap whereby the dampers are permitted individually to open by gravity at said gap between spaced sec tions, means for moving said sections individually into regulated positions to hold said dampers at selected angular positions with respect to their pivotal supports whereby to maintain the dampers in material retaining position and to control the flow of air between said dampers to the grate bars, and chute means located at said gap to receive the material discharged from the trough-like dampers at the gap.

5. A furnace chain grate comprising a driving chain, grate bars supported on said chain, and a plurality of dampers pivotally supported on said chain for movement therewith, and means for angularly adjusting said dampers about their pivotal supports, said means comprising longitudinally spaced runner rails both ends of which are independently and adjustably supported.

In witness whereof, I have hereunto signed my name this 20 day of September 1928.

ALFRED WILLIAM BENNIS.

.LLi) 

